It is planned to investigate extraocular and other muscles from humans, monkeys, and lower animals. The influence of aging, thyroid disease, strabismus surgery, nerve section, and central nervous system lesions will be evaluated. Investigation is to continue in an attempt to categorize the muscle fibers in extrinsic eye muscle and to associate the types of motor end plates and nerves that innervate each fiber. It is also planned to relate the types of muscle cells to different forms of eye movement by inducing chronic brain lesions and evaluating the histologic change within the muscle.